Resistive random access memory (RRAM) is a type of nonvolatile memory that provides the benefits of simple structure, small cell size, scalability, ultrafast operation, low-power operation, CMOS compatibility, low cost and so on. A RRAM comprises a memory element that may have a resistance changeable between two or more stable resistance ranges by applying an electrical pulse. A RRAM may further comprise components like top electrode, bottom electrode and so on. The materials used to form the memory element and other components of a RRAM may be chosen and adjusted. By this manner, a larger sensing window, a longer retention time, a better endurance and/or other improved aspects of performance may be achieved.